Hi,

I think tcp_output() is MP safe when called with shared netlock
together with socket lock.  This is the lock for tcpcb.  So let's
mark TCP protocol with PR_MPSOCKET.  Also t_oobflags is protected
this way.

ok?

bluhm

Index: kern/uipc_socket.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/kern/uipc_socket.c,v
diff -u -p -r1.347 uipc_socket.c
--- kern/uipc_socket.c	19 Dec 2024 22:11:35 -0000	1.347
+++ kern/uipc_socket.c	25 Dec 2024 15:41:36 -0000
@@ -927,9 +927,9 @@ soreceive(struct socket *so, struct mbuf
 		flags = 0;
 	if (flags & MSG_OOB) {
 		m = m_get(M_WAIT, MT_DATA);
-		solock(so);
+		solock_shared(so);
 		error = pru_rcvoob(so, m, flags & MSG_PEEK);
-		sounlock(so);
+		sounlock_shared(so);
 		if (error)
 			goto bad;
 		do {
Index: netinet/in_proto.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/in_proto.c,v
diff -u -p -r1.117 in_proto.c
--- netinet/in_proto.c	19 Dec 2024 22:10:35 -0000	1.117
+++ netinet/in_proto.c	25 Dec 2024 15:39:23 -0000
@@ -198,7 +198,7 @@ const struct protosw inetsw[] = {
   .pr_type	= SOCK_STREAM,
   .pr_domain	= &inetdomain,
   .pr_protocol	= IPPROTO_TCP,
-  .pr_flags	= PR_CONNREQUIRED|PR_WANTRCVD|PR_ABRTACPTDIS|PR_SPLICE,
+  .pr_flags	= PR_CONNREQUIRED|PR_WANTRCVD|PR_ABRTACPTDIS|PR_SPLICE|PR_MPSOCKET,
   .pr_input	= tcp_input,
   .pr_ctlinput	= tcp_ctlinput,
   .pr_ctloutput	= tcp_ctloutput,
Index: netinet6/in6_proto.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/in6_proto.c,v
diff -u -p -r1.121 in6_proto.c
--- netinet6/in6_proto.c	19 Dec 2024 22:10:35 -0000	1.121
+++ netinet6/in6_proto.c	25 Dec 2024 15:39:23 -0000
@@ -148,7 +148,7 @@ const struct protosw inet6sw[] = {
   .pr_type	= SOCK_STREAM,
   .pr_domain	= &inet6domain,
   .pr_protocol	= IPPROTO_TCP,
-  .pr_flags	= PR_CONNREQUIRED|PR_WANTRCVD|PR_ABRTACPTDIS|PR_SPLICE,
+  .pr_flags	= PR_CONNREQUIRED|PR_WANTRCVD|PR_ABRTACPTDIS|PR_SPLICE|PR_MPSOCKET,
   .pr_input	= tcp_input,
   .pr_ctlinput	= tcp6_ctlinput,
   .pr_ctloutput	= tcp_ctloutput,